I dont know if it would be strange to ask but if people were to submit either blue prints or drawings of gear that would work, would the developers take these and possibly incorporate them into the game?
Erm, i get that the players might make some good looking armour and weapons, but how is it unique if everyone can have it?, there'd be no point making armour for the game that only one player can use, it's a waste of space on the server, no matter how cool it is. I think customization should be part of the game, various honours and engravings allowed, but no full armour sets that you have to upload to the devs.
Following the lore is required in a 40k game, that said; it would be nice to have some slightly lore expanding items that are unique as a chapter relic or something similar.
Such customizations can be quite dangerous, cause soon there can be pink spacemarines shooting rainbows from dildos and charging enemies on ponies. It's o.k. & Slaanesh approves this, but... loyalist also will be able to do such stuff. And i REALLY afraid to see this in game. Some visual customization, consisting upon skins, decals, medals, other fancy GW-approved shinnies. But hey, this can be a good idea for some community-contest, when the best artworks will be chosen and adopted inside game by designers.
Something like that is what I intended whwn I posted this. Sorry, was late and I was tired so my brain wasnt working then.
Games like planetside2 or even Assault Horizon have/had skin design contests. Dark Souls had a shield contest. I could easily imagine a weapon "customization" contest as a form of marketing stunt. Take a classic weapon, and modify it "a bit" (we must still recognize it). Get votes. Implement in game or in the in-game store. Ex: the lazgun the guardsmen have in Space Marine. (I know it's not fanmade but it is a different variant of a classic weapon) Even with the GW approval part. Plus it's always a cool way of getting the community involved by participating and/or voting.
Would be cool to maybe have a Design a Relic contest like Disco said. The community could create some sketches or concept art for the weapon then submit it to the devs for votes/approval. I could see some awesome hammers, swords, shields, etc. coming out of that.